The first part of the eighth volume of Current Studies on the Indus Civilisation is an examination of inter-regional interaction and urbanism in the Greater Indus region of Pakistan and north-western India during the period that encompassed the development, existence and decline of South Asia's first urbanised society. The principal research objective is to identify the geologic sources from which the stone and metal artefacts excavated at Harappa -- a site that grew from a small village to become one of the largest Indus Civilisation cities, were most likely derived. Using techniques ranging from studies of basic macroscopic and mineralogical attributes to highly precise and accurate isotopic and elemental assays, grindingstone, chert, steatite, agate, vesuvianite-grossular, alabaster, limestone and various metal artefacts are directly compared to geologic samples of those materials collected from sources across South Asia. Geologic provenance determinations, periodised with reference to Harappa's detailed chronological sequence, are used to inform three lines of inquiry. The first two concern identifying the Harappans' inter-regional relationships, defining their extent and tracking them through time. The third involves elucidating synchronic variations in those relationships at the local or site level.